PHP function pack()

Availability in PHP 4.0

Pack data into binary string

Parameters

Parameter	Data type	Default value	Note
$format	string	not	The format string consists of format codes followed by an optional repeater argument. The repeater argument can be either an integer value or * for repeating to the end of the input data. For a, A, h, H the repeat count specifies how many characters of one data argument are taken, for @ it is the absolute position where to put the next data, for everything else the repeat count specifies how many data arguments are consumed and packed into the resulting binary string.
$args	mixed	null,
$_	mixed	null

Return values

string

A binary string containing data.

Other resources

Official documentation of the pack function